You should not assume you have HIV just because you have any of these symptoms. Each of these symptoms can be caused by other illnesses. And some people who have HIV do not show any symptoms at all for 10 years or more. If you think you may have been exposed to HIV, get an HIV test. Most HIV tests detect antibodies (proteins your body makes against HIV), not HIV itself.
The vessel which does not have the right-of-way has the duty to take positive and timely action to stay out of the way of the Stand-On vessel. Normally, you should not cross in front of the vessel with the right-of-way. You should slow down or change directions briefly and pass behind the other vessel.
Reverse is achieved by simply routing the water back toward the front of the boat. This is done usually with a reverse gate which is lowered down onto the nozzle stream. Neutral in a jet boat is simply a state where the reverse gate is somewhere between up and down and the forces are equal. That is why with many Jet boats you will find the neutral is really moving the boat very slightly forward or backward. You may have to adjust the lever to get it just right.